1. Field of the Invention
The present invention relates to a manufacturing method of a thin-film element having a stacked structure of thin films. In particular, the present invention relates to a manufacturing method of a thin-film magnetic head used for magnetic recording. Further, the present invention relates to a thin-film magnetic head used for magnetic recording, a head gimbal assembly (HGA) provided with the thin-film magnetic head, and a magnetic disk drive apparatus provided with the HGA.
2. Description of the Related Art
Recently, due to demands for large-capacity and downsizing of magnetic disk drive apparatuses, further improvement on recording density has become necessary. Important points in higher recording density include improvement on the intensity of write fields generated from a thin-film magnetic head. As a structure intended to improve the intensity of write fields, there has been disclosed in Japanese Patent Publication No. 04-006603A, a metal-in-gap head, which is a bulk head, including a metallic layer having a plurality of thin-films, for example. Further, in Japanese Patent Publication No. 10-105919A, there has been disclosed a thin-film magnetic head in which an upper distal magnetic pole is formed of a material having a high saturation magnetic flux density.
Recently, in order to respond to the higher recording density, there is a growing demand for a narrower track width of magnetic pole layers. However, when the track width of the magnetic pole layer becomes narrow, it becomes more difficult to secure a sufficient intensity of write fields. At the same time, the performance of a preamplifier for read and write operations of the thin-film magnetic head has been greatly improved, and thus, a larger write current can be input to an electromagnetic coil element for writing. The improvement on the performance of the preamplifier allows an improvement on the intensity of write fields while redeeming a problem of the narrower track width.
However, when the write current is increased under the narrower track width of the magnetic pole layer, a leakage field from the magnetic pole layer also increases. As a result, it becomes highly probable that unnecessary writing or erasure to an adjacent track on the magnetic disk, which is a magnetic recording medium, is performed.
In particular, in radially inward and outward portions of the magnetic disk, a skew angle, an angle of the head to a track, becomes too large. As a result, the magnetic pole layer on the leading side is brought close to the adjacent track. Consequently, it becomes more probable that the leakage field from the magnetic pole layer on the leading side causes unnecessary, writing or erasure to the adjacent track. As a measures thereagainst, the saturation magnetic flux density of the magnetic pole layer on the leading side can be limited to decrease the leakage field. However, the limitation inevitably lowers the intensity of the write field itself.
As another effective measure, the width in the track width direction in the magnetic pole layer on the leading side can be made smaller. In this case, the width in the track width direction in the magnetic pole layer on the trailing side defines a track width in a recording layer on the magnetic disk, and needs to be set to a width of a predetermined size to obtain sufficient intensity of write fields and field gradient. Therefore, the width of the magnetic pole layer on the leading side needs to be smaller than that of the magnetic pole layer on the trailing side. However, the magnetic pole layer on the leading side is positioned on the side opposite to a stacking direction of the magnetic pole layer on the trailing side on the element formation surface of a substrate. Thus, it is very difficult to achieve a configuration of such widths while securing a size of each magnetic pole layer and accuracy of the mutual positional relations.
In this case, the width of the magnetic pole layer on the leading side needs to be set to a predetermined value with high accuracy by taking into consideration various parameters such as the thickness of the magnetic pole layer or the like. Conventionally, a guideline therefor, however, has not been proposed at all.
Further, not only in the thin-film magnetic head but also in a general thin-film element, controlling such that the width of the layer on the side opposite to the stacking direction (on the lower side) on the element formation surface of a substrate is made smaller, has been very difficult to achieve, though necessary in various element configurations.